The present invention relates to an engine starting system for an internal combustion engine. In particular, the present invention relates to electromagnetically-actuated choke system for a small engine.
Internal combustion engines often include a choke system or assembly to regulate the air/fuel mixture to the engine during starting. A choke valve typically regulates the air flow to the engine during starting. A typical choke assembly includes a mechanical actuator to regulate the choke valve position. When initially starting an engine, the choke valve reduces the air flow to the engine to enrich the air/fuel mixture. During normal engine operation, the choke valve is not needed because the engine no longer requires a rich air/fuel mixture.
One embodiment of the invention provides an engine starting system for an internal combustion engine that includes a power source, an electromagnetic coil and core, and a choke valve disposed in an air intake of an air/fuel-mixing device of an engine. The power source provides an electrical signal to the electromagnetic coil. One embodiment of the power source includes at least one magnet positioned on a moving component during starting of the engine, and a stator coil positioned on a stationary part near the at least one magnet. At the time of starting the engine, the at least one magnet moves past the stator coil in such a way as to induce an electrical signal in the stator coil. The stator coil outputs the electrical signal to an electromagnetic coil and core. The electrical signal induces a magnetic field from the electromagnetic coil through the core. The magnetic field through the core moves the choke valve toward a closed position that enriches an intake mixture of fuel and air to an engine. In one embodiment, the magnetic field moves an arm interconnected with the choke valve. Upon interruption of the electrical signal from the stator coil, the magnetic field is interrupted and a spring returns the choke valve towards its original open position.
As noted above, the electrical signal to the electrical magnetic coil is induced by at least one magnet and its respective magnetic field moving past a stator coil. In one embodiment of the engine starting system, the at least one magnet is positioned on a flywheel and the stator coil positioned on a stationary component underneath the flywheel. For example, an ignition coil can be used as the stator coil. In an alternative embodiment, the stator coil can be separate from the ignition coil. In another embodiment, the at least one magnet is positioned on a pull rope, and the stator coil is positioned on a stationary component of the engine. In yet another embodiment, the at least one magnet is positioned on a rewind pulley, and the stator coil is positioned on a stationary component of the engine in the vicinity of the magnet. In yet another embodiment, the magnet and stator coil are located in a generator mechanically connected to the rewind pulley and pulley rope. The operator""s pull of the pulley rope moves the rewind pulley and interconnected generator to provide an electrical signal to the electromagnetic coil.
In yet another embodiment of the invention, the power source includes a battery, and the engine starting system includes a starter motor and a starter switch. The starter switch is electrically connected between the battery and the starter motor. The electromagnetic coil is electrically connected to the starter switch. When the starter switch is closed at starting, the battery supplies electrical power to the starter-motor and to the electromagnetic coil. The electrical power to the electromagnetic coil generates a magnetic field through the core. The magnetic field through the core causes the choke valve to move to a substantially closed position that enriches an intake mixture of fuel and air to the engine. When the starter switch interrupts electrical power to the starter motor and to the electromagnetic coil, a spring biases the choke valve to return to its original open position.
If either the non-ignition stator coil, battery, or electromagnetic coil fails during engine operation, the engine can continue to operate since the choke valve is biased to the open position. Also, the engine can still be started by manually holding the choke arm to a closed position.
Another embodiment of the invention further includes a temperature switch electrically connected between the negative terminal of the electromagnetic coil and electrical ground. Above a certain threshold temperature, the temperature switch interrupts the power supplied to the electromagnetic coil so that the choke valve remains in a substantially open position.
Another embodiment of the invention further includes a free-wheeling diode electrically connected between the terminals of the electromagnetic coil. After electrical power is interrupted to the electromagnetic coil, the free wheeling diode recirculates and dissipates the electrical current in the electromagnetic coil to enhance the response of the choke valve to an interruption of the electrical signal to the electromagnetic coil.
In a small engine application, the invention regulates the air intake of an air/fuel-mixing device based on electromagnetic actuation of the choke valve. Electrically connecting a temperature switch and free-wheeling diode provides an economical means for starting the engine at hot (versus cold) temperatures by keeping the choke valve open.
As is apparent from the above, it is an aspect of the invention to provide an exemplary engine starting system that regulates the intake of air to the air/fuel mixing device of an engine based upon electromagnetic actuation of the choke valve position. Other features and aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.